An escutcheon ES of a tape player has a cassette insertion aperture which is covered by a dust door to protect the interior of the tape player against dust. The dust door is configured to rotate into the interior of the tape player to open the aperture when a cassette is pushed thereinto. It is necessary to ensure that the rotated dust door never hits a cassette holder which is provided at the back of the escutcheon to accept the cassette inserted into the aperture. In this connection, a prior art arrangement uses a dust door having a width smaller than that of the cassette holder so that the dust door, when rotated, enters into the cassette holder and does not hit it.
The prior art arrangement is explained below, referring to FIG. 3. A dust door 12 is supported by right and left side walls 11--11 of the tape player pivotably about a shaft 13. The dust door 12 is biased by a spring 14 outwardly of the tape player to contact a stopper 11a provided at a front end of the side wall 11. The dust door 12 is smaller in width than a cassette holder 15 disposed in the interior of the tape player, so that the dust door 12 can enter within the width of the cassette holder when the dust door 12 is rotated into the interior of the tape player about the shaft 13. Outside the dust door 12 is located a cassette insertion aperture E provided in the escutcheon.
The cassette insertion aperture must have a width large enough to ensure smooth insertion of a cassette. That is, the width is necessarily wider than that of the cassette holder. Therefore, the dust door 12 narrower than the cassette holder 15 cannot fully shut the cassette insertion aperture E, and gap l.sub.1 exists between the dust door 12 and the cassette insertion aperture E. Obviously, this arrangement cannot protect the interior of the tape player effectively against dust.